Corrugated cardboard or fiberboard is widely used to package goods for transit. An outer sheet of liner (or “linerboard”) is glued to a fluted sheet to provide stiffness in the direction in which the flutes extend. A second outer sheet of liner can be glued to the fluted sheet opposite the first outer sheet to provide stiffness in the direction perpendicular to the flutes.
Moreover, markings are often printed on corrugated stock. For example, shipping boxes can be printed with edge-crush strength, gross weight, fragile, or this-end-up indicators. Printers typically operate using subtractive color: a substantially reflective receiver (piece of corrugated stock) is overcoated image-wise with cyan (C), magenta (M), yellow (Y), black (K), and other colorants. For example, U.S. Publication No. 2008/0159786 by Tombs et al., entitled “Selective printing of raised information by electrography,” published Jul. 3, 2008, the disclosure of which is incorporated herein by reference, describes electrophotographic printing using marking particles of a substantially larger size than the standard size marking particles of the desired print image. Tombs et al. also describe using non-pigmented (“clear”) marking particles to overlay raised information on an image. Markings can include multiple types of content. For example, a box can be printed with text, halftoned photographs, and line-art or other graphics.
Numerous schemes for manufacturing corrugated board have been developed. However, all conventional fluted cardboard has certain mechanical properties in certain dimensions, and those properties cannot readily be adjusted depending on the type of product to be packaged. For example, referring to FIG. 3A, a standard cardboard box is generally formed by stamping box blank 301 from a rectangular sheet of corrugated board. Box blank 301 is then folded along fold lines 302, and front surface 303 of tab 304 is glued to back surface 305 to form a manufacturer's joint. As a result, the direction F of extension of flutes 306 (FIG. 3B) is set across the entire box. The designer of the box cannot align flutes differently in different portions of the box. This restricts the box designer's freedom to adjust the mechanical characteristics of the box based on its intended use. For example, a box may need to have comparable strengths in the X and Y directions, corresponding to the horizontal portions of the box, but may need enhanced strength along the Z-direction in the vertical portion to permit the stacking of boxes without increasing the weight of the box unnecessarily. This relative strength configuration cannot be provided by conventional ways of making corrugated board, or by ways of making extruded plastic corrugations such as COROPLAST.
FIG. 3B also shows first liner sheet 310, second liner sheet 311, and fluted sheet 312 between them. Starch glue is conventionally applied at each area of contact between fluted sheet 312 and liner sheets 310 or 311.
Presently, shipping departments of companies need to stock a wide variety of boxes in order to ship products to customers. The boxes should be close in size, but larger than, the product to ship. Extra space in each box is filled with packing materials that add additional weight and cost. In addition, maintaining inventory of the packaging materials and boxes cost money and takes up space. It would be preferable to form a box that accurately fits the specific items to be shipped.
Moreover, the adhesives used in corrugated-box manufacturing have deficiencies. Starch-based adhesives are commonly used, but are water-soluble. Epoxy, glue and hot-melt glue change volume when they cool, producing internal stresses that can weaken the board.
There is, therefore, a need for ways of making corrugated board and packages that permit adjusting the mechanical properties and the directions in which those properties are effective. There is also a need for ways of making board using durable adhesives that do not create internal stresses in the board.
The disclosure of U.S. Patent Publication No. 2007/0196600 by Hutchinson et al. is incorporated herein by reference.